20.185. Release 0.75
The Hive S3 file system has a new configuration option,
hive.s3.max-connections, which sets the maximum number of connections to S3. The default has been increased from
The Hive connector now supports renaming tables. By default, this feature is not enabled. To enable it, set
hive.allow-rename-table=truein your Hive catalog properties file.
count()with a constant to execute as the much faster
Add support for binary types to the JDBC driver
The legacy byte code compiler has been removed
New aggregation framework (~10% faster)
approx_avg()function has been removed. Use
Fixed parsing of
UNIONqueries that use both
Fixed cross join planning error for certain query shapes
Added hex and base64 conversion functions for varbinary
LIKEoperator to correctly match against values that contain multiple lines. Previously, it would stop matching at the first newline.
Add support for renaming tables using the ALTER TABLE statement.
Add basic support for inserting data using the INSERT statement. This is currently only supported for the Raptor connector.
JSON Function Changes
SELECT json_extract(json, '$.store[book]'); SELECT json_extract(json, '$.store["book name"]');
As part of this change, the set of characters allowed in a non-bracketed path segment has been restricted to alphanumeric, underscores and colons. Additionally, colons cannot be used in a un-quoted bracketed path segment. Use the new bracket syntax with quotes to match elements that contain special characters.
The scheduler now assigns splits to a node based on the current load on the node across all queries.
Previously, the scheduler load balanced splits across nodes on a per query level. Every node can have
node-scheduler.max-splits-per-node splits scheduled on it. To avoid starvation of small queries,
when the node already has the maximum allowable splits, every task can schedule at most
node-scheduler.max-pending-splits-per-node-per-task splits on the node.
Row Number Optimizations
Queries that use the
row_number() function are substantially faster
and can run on larger result sets for two types of queries.
Performing a partitioned limit that choses
N arbitrary rows per
partition is a streaming operation. The following query selects
five arbitrary rows from
orders for each
SELECT * FROM ( SELECT row_number() OVER (PARTITION BY orderstatus) AS rn, custkey, orderdate, orderstatus FROM orders ) WHERE rn <= 5;
Performing a partitioned top-N that chooses the maximum or minimum
N rows from each partition now uses significantly less memory.
The following query selects the five oldest rows based on
orders for each
SELECT * FROM ( SELECT row_number() OVER (PARTITION BY orderstatus ORDER BY orderdate) AS rn, custkey, orderdate, orderstatus FROM orders ) WHERE rn <= 5;
Use the EXPLAIN statement to see if any of these optimizations have been applied to your query.
The core Presto engine no longer automatically adds a column for
queries. Instead, the
RecordCursorProvider will receive an empty list of
Block APIs have gone through a major refactoring in this
release. The main focus of the refactoring was to consolidate all type specific
encoding logic in the type itself, which makes types much easier to implement.
You should consider
Block to be a beta API as we expect
further changes in the near future.
To simplify the API,
ConnectorOutputHandleResolver has been merged into
ConnectorMetadata were modified to
This is a backwards incompatible change with the previous connector and
type SPI, so if you have written a connector or type, you will need to update
your code before deploying this release. In particular, make sure your
connector can handle an empty column handles list (this can be verified
SELECT count(*) on a table from your connector).